In industrial automation, there is requirement for measuring and acquiring data (data acquiring for short below) for the continuous physical signals such as temperature, pressure, flow, voltage, concentration, etc. The analog signals should be sampled through the analog sampling channel according to the requirement of the signal application terminals, and the sample frequency is fΔy. In order to avoid frequency mixing, it is required to set an analog low-pass filter, whose cutoff frequency fc<0.5×fΔy, in the analog sampling channel. Since fΔy is smaller, fc will be so small that cost and difficulty of the analog low-pass filter is increased.
Further, most of industrial automation adopts a steady state model which needs the data acquired steady state value of the physical signal. The Chinese Invention Patent No. ZL200910158375.x and ZL200910158370.7 (the inventor is HAO, Yushan and the invention title is “Measuring Device and Method for Continuous Physical Signal”) provides measuring and recording the steady state data and full state data for the common physical signal, but the output frequency does not accord with the above data acquiring frequency, and the output content is relative more (including start and stop time, etc.), thus it is not convenient to directly apply to the industrial automation.